This invention generally relates to nuclear reactor vessels, and specifically to a unique lifting fixture and related process for the core support plate.
In a nuclear reactor pressure vessel, the core support plate provides lateral support and guidance to the control rod guide tubes, peripheral support pieces, in-core flux monitor guide tubes, and start-up neutron sources. The core plate itself is formed with an array of holes through which the control rod guide tubes pass. The core plate assembly is bolted to a support ledge between the central and lower portions of the core shroud. During core shroud replacement procedures, the core plate is typically removed and transported underwater to another location where it is cut or sliced into multiple pieces for disposal. After removal and during transport, the core plate is typically supported in an upright orientation on a support stand provided with an annular array of vertical supports, each of which has a horizontal support ledge upon which the core plate rests. Because of the geometry of the core plate, as well as the configuration of certain cutting tools, it is necessary to flip the core plate to an upside down orientation prior to slicing to allow access to the support structure of the core plate on the underside.